fs/proc/bootconfig.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * /proc/bootconfig - Extra boot configuration
   4  */
   5 #include <linux/fs.h>
   6 #include <linux/init.h>
   7 #include <linux/printk.h>
   8 #include <linux/proc_fs.h>
   9 #include <linux/seq_file.h>
  10 #include <linux/bootconfig.h>
  11 #include <linux/slab.h>
  12
  13 static char *saved_boot_config;
  14
  15 static int boot_config_proc_show(struct seq_file *m, void *v)
  16 {
  17         if (saved_boot_config)
  18                 seq_puts(m, saved_boot_config);
  19         return 0;
  20 }
  21
  22 /* Rest size of buffer */
  23 #define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
  24
  25 /* Return the needed total length if @size is 0 */
  26 static int __init copy_xbc_key_value_list(char *dst, size_t size)
  27 {
  28         struct xbc_node *leaf, *vnode;
  29         const char *val;
  30         char *key, *end = dst + size;
  31         int ret = 0;
  32
  33         key = kzalloc(XBC_KEYLEN_MAX, GFP_KERNEL);
  34
  35         xbc_for_each_key_value(leaf, val) {
  36                 ret = xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX);
  37                 if (ret < 0)
  38                         break;
  39                 ret = snprintf(dst, rest(dst, end), "%s = ", key);
  40                 if (ret < 0)
  41                         break;
  42                 dst += ret;
  43                 vnode = xbc_node_get_child(leaf);
  44                 if (vnode && xbc_node_is_array(vnode)) {
  45                         xbc_array_for_each_value(vnode, val) {
  46                                 ret = snprintf(dst, rest(dst, end), "\"%s\"%s",
  47                                         val, vnode->next ? ", " : "\n");
  48                                 if (ret < 0)
  49                                         goto out;
  50                                 dst += ret;
  51                         }
  52                 } else {
  53                         ret = snprintf(dst, rest(dst, end), "\"%s\"\n", val);
  54                         if (ret < 0)
  55                                 break;
  56                         dst += ret;
  57                 }
  58         }
  59 out:
  60         kfree(key);
  61
  62         return ret < 0 ? ret : dst - (end - size);
  63 }
  64
  65 static int __init proc_boot_config_init(void)
  66 {
  67         int len;
  68
  69         len = copy_xbc_key_value_list(NULL, 0);
  70         if (len < 0)
  71                 return len;
  72
  73         if (len > 0) {
  74                 saved_boot_config = kzalloc(len + 1, GFP_KERNEL);
  75                 if (!saved_boot_config)
  76                         return -ENOMEM;
  77
  78                 len = copy_xbc_key_value_list(saved_boot_config, len + 1);
  79                 if (len < 0) {
  80                         kfree(saved_boot_config);
  81                         return len;
  82                 }
  83         }
  84
  85         proc_create_single("bootconfig", 0, NULL, boot_config_proc_show);
  86
  87         return 0;
  88 }
  89 fs_initcall(proc_boot_config_init);